The present invention relates to a process of making granulates or multiparticulates which are useful, for example, in pharmaceutical dosage forms. In particular, the invention relates to a process for melt-extruding pharmaceutical agents with excipients to form multiparticulates suitable for inclusion in solid dosage, forms such as capsules, tablets and the like.
It is known in the pharmaceutical art to prepare compositions which provide for controlled (slow) release of pharmacologically active substances contained in the compositions after oral administration to humans and animals. Such slow release compositions are used to delay absorption of a medicament until it has reached certain portions of the alimentary tract. Such sustained-release of a medicament in the alimentary tract further maintains a desired concentration of said medicament in the blood stream for a longer duration than would occur if conventional rapid release dosage forms are administered.
Over the years, several different methods of preparing controlled release pharmaceutical dosage forms have been suggested. For example, direct compression techniques, wet granulation techniques, encapsulation techniques and the like have been proposed to deliver pharmaceutically active ingredients to the alimentary tract over extended periods.
Melt granulation techniques have also been suggested to provide controlled release formulations. Melt granulation usually involves mechanically working an active ingredient in particulate form with one or more suitable binders and/or pharmaceutically acceptable excipients in a mixer until one or more of the binders melts and adheres to the surface of the particulate, eventually building up granules.
PCT International Publication No. WO 92/06679 discloses melt granulating methods for producing pellets containing therapeutically active substances. The method includes mechanically working a mixture containing the active substance in cohesive form with a binder having a melting point of 40-100xc2x0 C., while supplying sufficient energy to melt the binder and form xe2x80x9covermoistxe2x80x9d spherical pellets and thereafter adding an additional cohesive substance while maintaining the mechanical working to finally produce dry pellets.
PCT International Publication No. WO 93/18753 also discloses another melt extrusion process for preparing sustained-release pellets. This method includes pelletizing a mixture containing drug in finely divided form and a binder which includes one or more water-insoluble-wax-like binder substances with a melting point above 40xc2x0 C. using a high shear mixer.
In the spite of the foregoing advances, a need for further alternatives in the field of controlled release formulations has been sought. The present invention addresses this need.
It is therefore an object of the present invention to provide improved methods for producing multiparticulates containing pharmaceutically active ingredients and excipients.
It is a further object of the present invention to provide multiparticulates containing pharmaceutically active ingredients which display improved controlled-release characteristics.
These objects and others have been accomplished by the present invention, which relates in part to a unit dose sustained-release oral dosage form containing a plurality of melt-extruded particles, each of said particles comprising:
a) a therapeutically active agent;
b) one or more retardants; and
c) an optional water-insoluble binder.
The particles have an average length of from about 0.1 to about 12 mm and the unit dose provides a release of the therapeutically active agent over at least about 8 hours.
Another aspect of the invention provides a method of preparing a multiparticulate sustained-release oral dosage form. This method includes mixing together a therapeutically effective agent, a water-insoluble retardant and an optional binder to form a homogeneous mixture, heating the mixture and thereafter extruding the mixture into strands. The strands are then cooled, and reduced to particles having a size of from about 0.1 to about 12 mm. This aspect further includes dividing the particles into unit doses. The ratio of water-insolube retardant material to therapeutically active agent is sufficient to impart a release of the active agent from the multiparticulate system over an extended time period. In this regard, the retardant will comprise about 5-95% of melt-extruded multi-particulate. The multiparticulate sustained-release system can be included within a hard gelatin capsule or other oral dosage forms such as a compressed tablet. Methods of preparing such dosage forms are also provided herein.
In yet a further aspect of the invention, there is provided a method of treating a patient with sustained-release multi-particulate formulations prepared as described above. This method includes administering a unit dose sustained release oral dosage form containing the novel melt-extruded particles to a patient in need of the active ingredient contained therein. For purposes of the present invention, a unit dose is understood to contain an effective amount of the therapeutically active agent.
A still further aspect of the invention provides an alternative method of preparing a multiparticulate sustained oral dosage form. This aspect includes directly metering into an extruder a homogeneous mixture of a water-insoluble retardant, a therapeutically active agent, and an optional binder, heating the homogeneous mixture, extruding said mixture to form strands, cooling the strands and cutting the strands into particles having a size of from about 0.1 to 12 mm and dividing the particles into unit doses. The ratio of hydrophobic material, namely water-insoluble retardant (and optional binder) to the therapeutically active agent is sufficient to impart a controlled release of the therapeutically active agent from the melt-extruded particles and unit doses over a time period of at least 8 hours.